I have an application that runs in the background, I need it to pseudo randomly take a picture using the forward facing camera and send that to a database.
A possible solution I thought of was to use URL schemes to open another application, which will take the picture and send it, then use another URL scheme to open the background application back up. Does anyone know if this is possible?
Or perhaps there is a better solution.
It is not possible for an iOS application in the background to initialize, utilize, or grab photos from the camera hardware, let alone store or upload them to a local database.
Not only is this a security risk, but it poses a potential privacy invasion, and is just plain creepy. Besides, background apps only stay alive for 10 minutes or so, so even if this activity were possible, sustaining it would be impossible.
However, it is possible to use the camera directly from an active app without having to delegate the task to another application (perhaps you are thinking a little too much like an Android developer :p). Take a look at UIImagePickerController.
There's a very limited set of actions background applications can do—GPS, audio, phone & VOIP calls, and a couple of others. Accessing the camera is not one of those allowed actions, so you can't take a picture in the background.
As an alternative, you could set up a notification system to alert the user that it's time to take a picture (for whatever reason), and if they choose to open the app it could do your required actions then.
Related
I have an app that styles the user's photo, then saves and/or uploads to Facebook, etc..
My users have asked if they could save/upload to several services with one button click. So I've implemented a dialog that lets them choose which services to upload, and once you press the button, it uploads to each service, one at a time.
My worry is that if the user selects, say, 4 services and has a full res photo, it could take quite a bit of time for all that data to go up the wi-fi pipe, much less 3G.
Is there anything I should do besides put up a UIActivityIndicator and tell the user where his photo is going...and WAIT? It just bothers me that they could sit there for a long time, waiting for the network gods...
Any thoughts?
Thanks!
Make the upload asynchronous and backgrounded (using whatever 3rd party library you're using--wait you're not trying to do this with AFNetworking or something, are you??) and then use the Task Completion API to ensure the upload completes successfully even if they leave the app.
I'd go ahead and scale down the image some, too. If they're going to be looking at it on a website, there's no need for it to be full multi-megabyte.
It wouldn't hurt to add a display string that says "Uploading to Facebook...." then change it to "Uploading to Flickr...." etc. You'd be surprised at how faster your app seems if you let the user know that something is going on. (You could also use a progress indicator as well.)
I want to make an app that runs in the background so that if a user is reading a web page or PDF file on an iPhone or iPad, he can mark some words, see the meaning of those words, and then have those words stored in the app's database. He can then afterwards look for the words which he has learnt and increase his vocabulary.
Does the iOS 4 API allow that? What are the limitations? Advantages? Disadvantages?
Thanks in advance
No is does not, you can only run voip. audio or navigation apps in the background.
Only one app can run at a time, and installing one app cannot effect any built in app. So no, there is no way to achieve what you are trying for here.
Your best bet is to instruct users to copy the word, open the app, and then you can snag whatever is on the clipboard then.
(Note there are multitasking APIs, but you still cant access anything outside of your app even if you convince the OS to let you run in the background for a little while)
The docs don't seem to offer any guarantees - I'm just wondering if anyone's had any experience of uploading a large amount data after a user 'backgrounds' an iPhone app.
E.g., recording some audio or video and uploading it while there's the possibility that the user will start another app. Is is reasonable to expect to be able to be able to upload several MB of data in the background, perhaps using the VOPI UIBackgroundMode, which should keep sockets active?
First, uploading anything that is not VoIP data in a VoIP background mode violates Apple's guidelines and will probably get your app rejected. But you still have the option of using the normal background task completion API that gives your app another 10 minutes (at the moment, the amount might change in a future release) to finish a task like an upload.
If a foreground app uses a large amount of bandwidth, it is likely that the OS will give it priority over the background task.
Of course, you cannot rely on your upload being finished. If you run out of time, the system will notify you and you should try to resume the upload when the user reactivates your app. But you can't rely on a stable internet connection anyway, even if your app is in the foreground, so I don't really see the difference.
NO, this is not possible. i agree that it creates problems when you have a long operation to make but it is defiantly not possible.
I'm creating an app which connects to server and sends some text.
If network (both wifi or 3g) is there, it will immediately send the text to server.
But if there is no network, it keeps on polling for server connection every 5 minutes.
All this part is working fine.
But when using iPhone 4 device, i want the app to check for server connection even when app goes into background. So, when app goes to background and when network comes back, it must be able to send the text to server.
How can I achieve it? I've seen some apps where they say that the app will upload photos to server even in background. How will they do it?
I suggest you read this article from Apple carefully, especially the Completing a Finite Length Task in the Background section.
http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/BackgroundExecution/BackgroundExecution.html
Something to clarify:
Once your app is in the background and is frozen by the OS, there would be no way for your app by it self to wake up and re-connect to the internet.
However, according to the article above from Apple, you can call this beginBackgroundTaskWithExpirationHandler method from your app's delegate to apply for additional time when put in the background, which is to say, though your app cannot wake up by it self when in background, it can, when in the background and not frozen, try to apply for additional time to finish its lengthy task.
Hope it helps.
There is a trick that I think flayvr is using.
If you download and use the app, you will see that they require you to enable your location.
And why is that?
because they want like you to do something in the background even when the app is terminated (they creating an album out of your newly captured photos), and how do they do that?
They use the significant location change, where when someone is traveling some significant distance (something like 500m) each app that registered for significant location change will get awaken for a limited amount of time to perform some quick task and will be terminated in a few seconds.
So your app can register to that event also and when the event of significant location change fired you will be able to send the text to server (quickly).
Hope that helps.
Until now you can do that on iOS7 with Background Fetch.
Take a look at this article.
However you only have up to 30s to get the task done.
According to the article above, there's also another solution called Background transfer service.
If more time is required though, then the Background Transfer Service
API can be used
Create a new project in Xcode and you will see there are bunch of new methods auto generated in app delegate file. like applicationDidEnterBackground, applicationWillEnterForeground etc.
read the description you have to call your thread to upload data on server here.
I need to write an application, that every 10 minutes it should be awaken from suspended mode, get user location via gps and send this information to the server by network.
Depending on the response it should return to the suspended mode or show local notification to the user.
Is there a way to do this on iOS 4?
I've tried different approaches, but the only working for me was to start monitoring user location in backgroind and declare the application as location background application. In that case it worked in background and has a network connection. But this approach takes a lot of power and not accepted cause application should work 24/7.
May be there is a way to write some daemon that should work in background and wake my application every 10 minutes?
Apparently, Pastebot tried to do something similar with the 'audio' multitasking declaration (by playing a silent audiofile) and got rejected.. UNTIL they actually presented a option to the user to pick which audiofile they wanted to play. It's in the appstore now. :)
In this case: What is your reason for not wanting to use the location updates? If battery-usage is a concern, you can use the 'significant location changes only' option, after which you can temporarily change to a more accurate option.
This isn't possible outside of the method you have already tried.
The iPhone background task API will allow you to run a location service in the background.
There is no way to write daemons for the iPhone without jailbreaking, and that is not something I'm able/prepared to help you with.
App store friendly: use new APIs in iOS4, which allows u to make use of GPS location
Anti App store: create a daemon by adding a specific plist file to System/Library/LaunchDaemons/ and put ur app under Applications/. this approach requires a jailbroken iPhone however...
detailed information plz google the following keywords: daemon, multitask, background, etc...
cheers, Lloyd